High-purity quartz (HPQ) mining and processing

Why the concentration exists

High-purity quartz is defined as quartz products with SiO2 purity greater than 99.9%, with classifications ranging from low-end 3N to high-end 4N8 and ultra-high-purity grades reaching 6N-7N. Structurally bound substitutional elements such as aluminium, titanium, and lithium are impossible to remove through processing, which means the geological source determines the maximum achievable purity. The Iota 8 grade from Spruce Pine reaches 99.9992% purity and commands approximately $10,000 per ton.[5][13][23][24]

Only three mature pathways exist globally for natural ultra-pure quartz ore: Spruce Pine in North Carolina, Kyshtym in Chelyabinsk Russia, and Øverby in Norway. The Spruce Pine deposit consists of alaskite pegmatite rocks that contain uniquely pure ore bodies formed under specific geological conditions. Sibelco states its Spruce Pine facility has mine life potential exceeding 100 years sourced from these two uniquely pure orebodies.[1][10][25][26]

Processing high-purity quartz involves a sequence of ore dressing, calcination at 850-900°C, water quenching, milling, magnetic separation, electrostatic separation, pickling, deionized water cleaning, and drying. Air jet milling is the only grinding method that can control iron increase to less than 0.05 ppm because it introduces almost no metal contamination. Challenges remain in managing complex mineralogy, high reagent consumption, and operational costs throughout the purification process.[4][25][28]

What the evidence shows

Who supplies it

Sibelco and The Quartz Corp mine feedstock from their own operations at either end of a single alaskite pegmatite at Spruce Pine, North Carolina. Sibelco supplies about 80% of the high-purity quartz used by the chip industry according to industry reporting. Both companies operate their own processing facilities at the site, which produces an estimated 180,000 to 200,000 tons of high-purity quartz per year.[1][6][7][15]

Sibelco holds over 90% market share in international high-purity quartz sand products of 4N8 purity and above. The company monopolizes the international market for high-end quartz sand products with 4N8 purity and above. Sibelco has mined in the Spruce Pine area since 1970 under its former name Unimin, which merged with Santrol to form Covia in 2018 with Sibelco as the holding parent company.[11][12]

Alternative HPQ suppliers include Pacific Quartz in China with annual production capacity of 20,000 tons as of 2021, and Russian Quartz operating the Kyshtym deposit with capacity of 6,000 tons per year as of 2022. The Quartz Corp operates a facility in Norway with licensed annual production capacity of 30,000 tons of high-purity quartz. Additional suppliers include Homerun Resources with operations in Brazil and Canada, Mineracao Santa Rosa, and Nordic Mining ASA.[7][11][17][19][21]

What it depends on, and what depends on it

High-purity quartz from Spruce Pine is sourced from pegmatite rocks that are concurrently mined to produce feldspar and mica as byproducts. Sibelco's Spruce Pine site conducts mining and mineral separation steps for HPQ production with feldspar and mica as secondary outputs. The Quartz Corp estimates it has decades of reserves in its existing mines with additional reserves available in planned future mines.[2][6][9]

HPQ is used to produce fused quartz crucibles for manufacturing silicon metal ingots that are later processed into silicon wafers for photovoltaic and semiconductor markets. Additional end uses include high-temperature lamp tubing, specialty glass, optical fiber, and quartz lighting products. The major industrial markets for ultra-high purity quartz are China for solar PV and the US, Japan, Korea, and Taiwan for semiconductor chips.[2][26][27]

High-purity opaque quartz glass for the semiconductor industry requires that the total amount of 16 impurity elements does not exceed 20 micrograms per gram. The photovoltaic industry standard allows total impurity content up to 30 micrograms per gram for the same 16 elements. High-purity quartz leaching purification using OL reagent achieved 92.65% removal rate of impurity elements with total impurity content of 16.98 micrograms per gram under optimized conditions.[18][22]

Where it sits in the stack

What would break it

Hurricane Helene devastated Spruce Pine in late September 2024, halting extraction and distribution from the district that supplies about 80% of the world's high-purity quartz. The Quartz Corp paused its high-purity quartz operations on September 26, 2024, while Sibelco resumed mining with production and shipments progressively ramping up to full capacity as of October 11, 2024. The disruption highlighted the geographic concentration risk of having the dominant supply source in a single location.[14][20]

The supply chain maintained more than three months of quartz inventories to cushion the impact of the Spruce Pine mine shutdown. The Quartz Corp did not expect a critical situation for industries using the quartz due to existing stock and finished products throughout the supply chain. This inventory buffer prevented immediate disruption to semiconductor and solar manufacturing during the production halt.[7][14]

Incumbent and junior producers have been raising production outlook and expanding capacity, especially in mid-stream processing, which could weigh on future HPQ prices if expansion proceeds faster than expected. However, analysts remain conservative on actual capacity commencement speed and expansion volume of high-end supplies overall. The constraint has less to do with availability of processing capacity and more to do with scarcity of potential mined supply comparable to Spruce Pine.[3]

What to watch

Sibelco's $200 million Expansion 1 at Spruce Pine, announced in April 2023, is on track to double HPQ installed capacity by 2025. The company increased HPQ production by over 70% from 2019 to 2023 through process efficiencies and initial benefits of the first expansion phase. Sibelco's Expansion 2 at Spruce Pine is estimated at $500 million and scheduled for execution between 2024 and 2027.[8][10][15]

High Purity Quartz Limited holds a Champagne Quartz deposit under granted mining lease in Queensland with multiple large-scale exploration targets to be drilled commencing in 2025. The Pre-Feasibility Study supports estimated capital expenditure of A$525 million to commence production by Q1 2028. The project plans 36,000 tonnes per annum finished product capacity with 35% yield of saleable product from Run-of-Mine material.[16]

Related nodes

Sources

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2. pubs.usgs.gov
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